The background description provided herein is for the purpose of generally presenting the context of the present disclosure. The subject matter discussed in the background of the present disclosure section should not be assumed to be prior art merely as a result of its mention in the background of the present disclosure section. Similarly, a problem mentioned in the background of the present disclosure section or associated with the subject matter of the background of the present disclosure section should not be assumed to have been previously recognized in the prior art. The subject matter in the background of the present disclosure section merely represents different approaches, which in and of themselves may also be disclosures. Work of the presently named inventors, to the extent it is described in the background of the present disclosure section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Processing cell-containing liquid samples includes separating biological fluid components from a biological fluid. For example, separating biological fluid components from a biological fluid may include separating biological cells from other medium in a cell fluid. In one example, a process of cell therapy may include a method that a part of cells is isolated and extracted from human and/or animal tissues or peripheral blood and then the processed cells are implanted into humans and/or animals, or modified and cultivated in vitro before implanted into humans and/or animals. The process in cell therapy may include the process of cell isolation, modification and cultivation in vitro. For example, during Chimeric Antigen Receptor T (CAR-T) cell preparation, the whole process may be divided into steps of peripheral blood collection; peripheral blood mononuclear cell (PBMC) separation; cell separation of one or more specific populations; cell activation; cell cultivation; viral transfection; cell multiplication; cell concentration; cell wash; solvent preparation; and/or cell implantation. Different cell preparation methods may have one or more different implementations based on different processes. The one or more different implementations mainly involve cell separation of one or more specific populations; cell activation; cell cultivation; and virus transfection.
Among the cell preparation processes, cell concentration may include the process of separating biological fluid components from a large volume of a biological fluid, down to a small volume. For example, the large volume of a biological fluid may be stored in a large cultivation system (e.g., from a few hundred milliliters to 20 liters) and a small volume may be implemented by a small solvent preparation system (e.g., usually 100-500 ml). The concentration ratio may be more than 10 times. Most of the clinical cell therapies may be operated in one or more closed systems. Specifically, the whole process from cell collection to cell implantation may be completed in a closed system. Thus, the biological fluid may be prevented from contacting with outside environment and the risk of pollution and cross-contamination is reduced. Therefore, how to separate biological fluid components from a large volume of a biological fluid, down to a small volume in a closed system is a critical technical aspect in the cell preparation process.
The current technology for cell concentration may be mainly divided into two methods. The first method is carried out by a centrifugal system. Through a barrel-shaped centrifugal device, a cell-containing liquid sample is pumped into a barrel, centrifuged, and the waste liquid is discharged. Then the sample is pumped into the barrel again, and the centrifugal process is repeated until the centrifugation and concentration processes of all the sample are finished. The disadvantage of the first method is that the concentration process is time-consuming. It usually takes several rounds of centrifugation, and each round takes about 3-20 minutes for cell concentration. Furthermore, the volume of centrifugal barrel is limited, so that only limited sample can be concentrated in each round. It usually takes about a number of hours, for example, 10 hours, to concentrate 10 liters of the sample. Meanwhile, the cell survival rate is seriously reduced by using this method. Therefore, the first method may not be suitable for cell liquid concentration with a large volume.
The second method is achieved by using hollow fiber or membrane filtration. The second method usually uses a membrane with uniform pore sizes. Under the effect of the tangential flow, the cells are throttled on one side of the membrane and the waste liquid passes through the membrane, and then the objective of cell concentration is achieved. However, how to control liquid pressure and liquid flow rate is important. If liquid pressure is increased and the liquid flow rate is kept constant, the cells may experience high pressure and the membrane system may be easily blocked. Thus, the concentration efficiency may be decreased, and the cell survival rate may be reduced. Conversely, if the liquid pressure is decreased, the cell concentration efficiency may be low. It may take a long time to concentrate the same volume of cell liquid. If the flow rate of the sample is increased, the concentration efficiency may be reduced. In the meantime, the cells may experience increasing friction and the cell survival rate may be reduced. If the flow rate is reduced, cells may be precipitated and the membrane surface may be blocked, thus the concentration efficiency may be gradually reduced.
Therefore, the methods of controlling liquid pressure and liquid flow rates are key points of the membrane filtration system. The efficiency of cell concentration can be improved by increasing the surface area of the membrane in the membrane filtration system. However, the larger the surface area of the membrane, the cost may be higher. Therefore, the second method may not be suitable for cell concentration.
Most of the cell preparation processes involves cell cultivation and multiplication in vitro, through which the biological fluid is concentrated from a large cultivation volume (e.g., from a few hundred milliliters to 20 liters) to a small solvent preparation volume (e.g., usually dozens to hundreds of milliliters) that can be implanted to the human body. Accordingly, how to concentrate a sample from a large cultivation system to a small solvent preparation system in a closed system remains a problem. In the process of cell concentration, a number of parameters such as cell recovery rate, cell survival rate, and time may be assessed. However, the current cell concentration method and device that utilized cannot satisfy the industry requirements for cell preparation.
In the meantime, the current technology of cell therapy often involves cells that are extracted from and implanted to the same object. It may be important to consider during cell preparation that how to produce drugs with a similar standard based on different cells from different patients; that is consistent cell preparation. The cell preparation process often uses one or more single disposable products; thus, the current systems of rapid concentration cannot meet the needs of cell preparations. Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.